About PFAS

Per- and polyfluoroalkyl substances (PFAS) are a group of manmade compounds that have been in use for more than 70 years and are widespread in the environment. Resistant to heat, water and oil, PFAS are found in a wide range of products used by consumers and industry, such as:

A blue icon representing dental floss
Dental Floss
A blue icon representing lipstick and cosmetics
A blue pizza box icon
Pizza Boxes
Blue icon representing a cooking pot
Non-stick cookware
Blue icon representing rolled-up carpet
Carpeting & rugs

Quick PFAS facts

Can PFAS be removed from wastewater & biosolids?

PFAS compounds are difficult to break down because they are manmade and complex. They are often called “forever chemicals.”

There are currently no cost-effective options for removing PFAS from wastewater and biosolids.

The best way to eliminate PFAS from all water and in turn, biosolids, is to prevent it from entering the wastewater stream altogether. This is achievable through source reduction and elimination.

What are the current Regulations for PFAS?

In the absence of enforceable national PFAS standards for any media (drinking water, groundwater, surface water, biosolids, etc.), the state of Wisconsin is working on standards for PFAS, beginning with a groundwater standard.

Because each medias has a different level of risk and exposure pathways, different standards are necessary for each media.

In addition, given the pervasive nature of PFAS, standards or limits must account for the background levels of these compounds in our everyday lives.

Where PFAS compounds are found?

PFAS are abundant in our society and given the wide use of PFAS-containing products, there are background levels of PFAS compounds in household dust, human blood, even national forests. These levels are in the parts per billion (ppb) and parts per trillion (ppt) range.

Where PFAS compounds have been problematic is primarily the result of use in firefighting foam, chrome plating and industrial sources that use or manufacture PFAS.

Is there PFAS in wastewater and biosolids?

Wastewater treatment plants are not original sources of PFAS but “receivers” of these chemicals as used by manufacturers and consumers. Wastewater treatment plants do not add or have the capability to remove these compounds during the treatment process.

Given the widespread use of PFAS, there are background levels from PFAS in wastewater and biosolids.

Learn more about the District’s biosolids program in this fact sheet.

How much is a part per billion and a part per trillion?

The concentration level of PFAS is measured at an infinitesimal scale, typically parts per billion, or ppb, and parts per trillion, ppt. In fact, it’s only been in the last 10 years or so that the scientific community has had the ability to measure trace amounts in the parts-per-trillion range and the ability to detect compounds at that level.

To put that in perspective:

1 PPB =

1 second in 31.5 years
1/2 tsp in an Olympic-size pool

1 PPT =

1 second in 31,500 years
1 drop of water in 20 Olympic-size pools

1 PPB =

1 second in 31.5 years
1/2 tsp in an Olympic-size pool

1 PPT =

1 second in 31,500 years
1 drop of water in 20 Olympic-size pools


We have developed several fact sheets to help you better understand PFAS is it relates to wastewater and biosolids.

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